In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.

Seventh-day Adventists are known for living long, healthy lives. One famous follower of Adventism was Dr. John Harvey Kellogg. In the late 1800s the doctor took over operations at the Battle Creek, Michigan, sanitarium, a Seventh-day Adventist holistic healing center. (Kellogg eventually left the Adventist Church due to doctrinal and administrative differences.)

At the sanitarium Kellogg promoted a vegetarian diet, claiming that since humans and primates had similar digestive tracts, people should follow a natural diet rich in fruits, vegetables, nuts, and grains. Kellogg concocted healthy alternatives to vary the menu for patients. Kellogg found that by steaming—rather than grinding—wheat and putting it through rollers, he could make wheat flakes. He served these flakes to patients as a ready-to-eat breakfast cereal. Another favorite among the patients was Kellogg's mixture of oatmeal and cornmeal together, which he baked into a biscuit and then ground into bits. He called it granola.

The popularity of these breakfast foods soon transformed Battle Creek. Copycat cereal manufacturers popped up overnight, and the town became the birthplace of the cereal industry. Kellogg's more business-minded brother, W. K. Kellogg, had assisted John Harvey with odd jobs at the sanitarium. W. K. wanted to mass market the flaked foods, but his older brother preferred to keep production on a smaller scale. W. K. went on to create the Kellogg company, which today markets corn flakes and many other brands of cereals (with sugar added).

Even patients profited from John Harvey Kellogg's nutritional advice. C. W. Post, an inventor, had been admitted for an upset stomach. Post liked the cereal-based coffee substitute served at the sanitarium so much that after he left, he tried to convince Kellogg to partner with him and sell a coffee substitute to the public. Kellogg declined. Post moved ahead on his project, sold the coffee alternative, and became a multimillionaire. Today his Post cereal company is also known for its Grape Nuts and Post Toasties, among other products.